The present invention relates to a method for producing a semiconductor device, more particularly to a method for producing a semiconductor device on a single crystallized region which is formed in a concave portion of an insulating layer by melting polycrystalline silicon or amorphous silicon therein.
In one method for forming elements in a semiconductor device, proposed by the present inventors in Japanese Unexamined Patent Publication (Kokai) No. 55-98397 and Japanese Patent Application No. 56-154012 (filed Sept. 30, 1981), concave portions are formed in an insulating layer formed on a substrate, a polycrystalline silicon layer is formed on the insulating layer, and the polycrystalline silicon is melted by irradiation with a laser, electron beam, lamp, or other energy ray over the polycrystalline silicon layer to cause the polycrystalline silicon to flow into the concave portions, thereby forming single crystallized regions therein.
The problem with this method is that while the upper surfaces of the resultant single crystallized regions in the concave portions should be level with the nonconcave portions of the insulating layer, this is difficult in practice. When the molten polycrystalline silicon flows into the concave portions, more tends to flow into some portions than others. This results in some single crystallized regions protruding above and other regions recessed below the level of the nonconcave portions of the insulating layer. Further, some of the molten polycrystalline silicon may not flow into the concave portions and will remain on nonconcave portions. These problems complicate the process of production of the semiconductor device.